Multiple push button electrical switch apparatus



Jan. 19, 1965 .1.w. FELDMAYER 3,166,644

MULTIPLE PUSH BUTTON ELECTRICAL. SWITCH APPARATUS JOHN W. FELDMAYER Fig. 1

Jan. 19, 1965 C J. wf Fl-:LDMAYER 3,156,644

MULTIPLEI PUSH BUTTON ELECTRICAL SWITCH APPARATUS INVENTOR. JOHN W. FELD MAYER ATTORNE Jan. 19, 1965 1. w. FELDMAYER MULTIPLE PUSH BUTTON ELECTRICAL SWITCH APPARATUS 4 Sheets-Sheet 3 Filed Deo. 27, 1961 INVENTOR. JOHN W. FELD MAYER ATTORNEY Jan. 19, 1965 .1. w. FELDMAYER 3,166,644

MULTIPLE PUSH BUTTON ELECTRICAL SWITCH APPARATUS Filed Dec. 27. 1961 4 Sheets-Sheet 4 I eab 68) l LSV Seac E l l i l I 6 2 I I l a l' I J l J .E690 .DSSD 696 l l Z69d I l V' l INVENTOR.

F 6 JOHN W. FELDMAYER www ATTORNEY The invention described herein may be manufactured and used by or yfor the vGovernment of the United States of America `for governmental purposes without the pay- `ment of any royalties thereon or therefor.

This invention relates to `an electrical switch apparatus and moreparticularly to an arrangement of push button operated electrical switches for connecting one, electrical circuit with another of -a predetermined group.

Multiple electrical switches, as known in the prior art wherein individual switch operations are interlocked to insure the proper connection of certain electrical circuits while preventing other connections, vhave'usually been limited to a relatively few electrical circuits or else complex electrical or mechanical switching systems were required. lAs'more selectively connected electrical circuits appear in equipment design and greater flexibility is demanded, there is also an increasing needfo'r more efficient and less complex switching systems. For example, in airborne instrumentation the responsibility for correct switching operation was placed on lthe pilot and crew in defer-` ence tol increasing the'weight and losing valuable aircraft space yby adding heretofore available multiple electrical switches. Such aVV responsibility oftentimes is intolerable in this'technological era wherehuman error has not substantially been changed. 1

. Accordingly, it is `an objectv of the present .invention to provide an improved multiple push button switch apparatus for selectively connecting one electrical circuit with `ano-therof a group of circuits while preventing the connectionof other circuits in which depressing any single push button will release certain other push buttons, and in which a single release f.mechanisrn will release certain other pushbuttons.

Another object of the invention is to provide an improved multiple push button switch 'apparatus in whichv the push buttons are divided into two rows mechanically interconnected so that depressing any push button inl oney row wil-llprevent depressing certain push but-tons in the other row, in which depressing any one push button-1in either row will release any other depressed push button in the same row, and in which the depressing of release buttons associated with both rows will clear the respective row of any depressed push button.

Another object of the invention is to provide an improved push button switch apparatus for selectively establishing various combinations of circuits while preventing other combinations and which is relatively simple in design and construction, rugged and reliable; compact and' lightweight, and inexpensive to manufacture.

Various other objects and advantages ywill appear from the following description of one embodiment of the inl vention, and the most novel features will be particularly pointed out hereinafter in connection with theappended claims.

In the drawings: Y v

FiG. l diagrammatically represents a longitudinal top view of a multiple pushl button switch apparatus embodying the principles and concepts of the present invention;

FIG. 2 diagrammatically represents a transverse crossse'ctional View of the apparatus as taken along the line 2-2 of FIG. l;

l relative to the top .and bottom plateszitl and ll.

Jbii Patented dan. lli, 1965 lCC n n FIG. 3 diagrammatically represents a longitudinal crosssectional view of the apparatus as.y taken along the line .2*3 of FIG. 2; I s

FIGS. 4a, band c diagrammiatically represent fragmentary longitudinal cross-sectionalviews of the apparatus as taken along the lines @Q -4a, 4b--4ib and llc-lc of FIG. 3;

FIG. 5 represents a fragmentary isometric view of selected elements'of the apparatus for demonstrating the modus operandi; and f FIG. 6 diagrammaticaliy represents typical lock-out beams of ythe apparatus illustrated in FIGURES 1 ythrou gh 5.

in the illustrated embodiment of the invention, primary structural support for the push button switch apparatus obtains from a generally rectangular rigid frame having a rectangular top plate lll and a rectangular bottom plate ll held in parallel and opposing spaced relationship by a pair of parallel rectangular side channel plates l2 and lil secured at its side flanges along the longitudinal edges of the plates lo and ll in opposing relationship. The terms c push buttons individually identilied by the letters L 'through V. However, it is contemplated that the particular number of push buttons in each row may be varied by one skilledin the art to suit specifications orl circuit requirements without departing from the spirit of the invention herein disclosed. The push buttons may be constructed of transparent materials for edgev lighting of appropriately inscribed legends thereon.

Each push button of the row 16 is mounted on one side of a llat elongated plunger i8 having its planar surfaces normal to the longitudinal axis of the frame and one end extending through the top plate ill. Each plunger 1S has its other end extending through the bottom plate ll and is vertically slidable for a limited distance along its length The upward travel of each plunger i3 is limited by the upper end of an elongated flange i9 fixed along the outer side edge of the plunger l `at a right angle thereto. A plunger ,spring 2l `acting in compression between thebottom plate lll and a collar 22 on the lower portion of the plunger lll urges the plunger 18 upward until the flange 19 abuts the top plate lll. The downward travel of each plunger It is limited by the fully compressed length of the spring 2l. The flange i9 defines a vertical arrayof eight saw-tooth notches 23 equally spaced along the length thereof and opening toward the left as illustrated in FIG. 4a. One edge of each notch 23 is substantially normal to the length of the plunger 1S, and the other edge is sloped from the root of the notch 23 toward the upper end of the flange 19. When all of the pl'ungers lil are in a normally upward position with the flanges 19 abutting the top plate it, the respective notches 23 along the length of the anges i9 form eight notch tiers. Selected notches in each tier operatively engage follower studs 24 to produce horizontal motion thereof in a manner as will be now described.

Adjacent to each tier of saw-tooth notches 23 in the flanges i9, there are eight sliding bars Ze running parallel along the length of the sidey plate l2; The bars 25 are maintained parallel to each other by a plurality'of equally spaced rectangular notches along the side edges of a pair of end plates 27 and 23 which also form a part of the CTI ing with predetermined notches 23 of theadjacent tier.

The sliding ,bars 26 are biased toward the right so that any follower studs 24 thereon are continuously contacting the sloping edge of the saw-tooth notch 23. A slide bar compression spring 33 disposed between the end plate'ZS and a channel extension 34 on the right end of each sliding'bar 26, provide the biasing force. It should now beapparent that when any push button in row 16 is depressed, the sloped edges of the corresponding notch 23 will cause any follower stud 24 registering therein to move toward the left. The sliding bars 26 to which this studV 24 is attached will also move therewith. Each sliding bar 26 may be adapted to actuate one or more electrical switches 25 by spring clip actuators 30 secured t the sliding bars 26 by the studs 24. The illustrated embodiment shows two switches 25 actuated by only the first, fourth and seventh sliding bars 26 from the top. It is contemplated that similar switches be mounted on the side plate 12 for actuation by the remaining sliding bars 26.

Positioned along the length of the apparatus and nested in a tier of cutouts in the plunger 18 near the bottom thereof, a locking bar 36 slidably protrudes at the ends thereof through the plates 27 and 23 and is urged toward the right as viewed in FIGS. 4dr-4c by a locking bar compression spring 37. The plate 28 and a flange 38 fixed on the right end of the locking bar 36 provide reaction surfaces for the spring 37. The sides of the locking bar 36 are parallel to the side plates 12 and 13 with the upper edge defining a plurality of hooks 39 opening toward the right and spaced along the length thereof so that each hook registers witha rectangular aperture 41 'in the plunger 18 when the corresponding push button is fully depressed against the force of its spring 21. The lower edge of thehook 39 is substantially normal to the length of the plunger bar 13 for positive retention of the plungers 18 when the hook 39 is inserted into the aperture 41. The outer edge of the hook 39l is beveled to impartmotion of the locking bar 36 to the left'against theforce of the spring 37 when any plunger 1S is depressed. The locking bar 36 returns to the right when the lower edge of the hook 39 clears above the lower edge of the aperture 41 and thereby locks the plunger 18 in the downward and kfully depressed position.

As shown in FIGS. l-4c, all of the push buttons are in the non-depressed position with the follower studs 24 cornpletely seated in the corresponding notches 23. In this position, the apertures 41 permit the locking bar 36 to move rightward until the upper beveled edge of each hook 39 abuts bottom edge 42 of the plunger 18. It will be observed that the lower edge of each hook 39 is also beveled to insure that all of the hooks 39 will be disengaged from the respective apertures 41 and the plungers 13 can return to the non-depressed position irrespective of slight longitudinal misalignment of the ends of the hooks 39 with the apertures 41.

Adjacent to the end plate 27 and alignedwith the push button row 16, there is a slidable release rod 43 extending through the flanged portion of the end plate 27 and the top plate 1t). A release rod spring 44 connected in tension between the top plate and a lateral pin fixed on the release rod 43 urges the latter upward. A collar 46 fixed to the rod 43 engages the end plate 27 to limit the upward travel. The lower end of the release rod 43 includes an inclined cam surface 47 operatively engaging a lateral locking bar pin iii fixed near the protruding left end of the locking bar 36. In its non-depressed position, as shown in FIG. 4a, the lowest portion of the cam surface permits thelocltingbar 36 to move toits maximum right position. When the release plunger 43 pression of the spring 37' until the hooks 39 are completely withdrawn from the apertures 41 of the plungers 1S. In this manner, the release plunger 43 releases or clears all of the push buttons in the row 16 from a depressed position. v

The particular plunger construction set forth thereby provides for actuating of a multiplicity of electric switches directly and indirectly as will be now shown. The end of each plunger 18y which extends below the bottom plate 11 includes a double acting spring clip 51 secured thereto for operating armatures of opposed snap-acting switches 52, such as Microswitches, mounted on a channel plate 53 secured under the bottom plate 11 by flanges 54. Therefore, when the plunger 18 is depressed, the switches 52 are directly actuated through the spring clip 51. Similarly, some of the follower studs 24 secure a double acting spring clip 56, only one being shown for simplicity, to the sliding bars 26 which extend through apertures 55 in the side plate 12. The spring clips 56 operatively engage the armatures of snap-acting switches 57 mounted on the side plate 12. It should bel obvious, that except for space limitations up to 18 snap-acting switches-,could be actuated by a single plunger 18 of the illustrated embodiment. Obviously the number can be varied,1for instance, by varying the number of notches 23 in the Y and structural details to the plunger bar 18 ofthe pushV button row 16.

If any push button in one row is maintained depressed, only certain push buttons of the other row 'can be depressed to actuate switches simultaneously. This is accomplished by a plurality of lockout beams 61, 62, 63 and 64, in descending order, equally spaced from the top Y plate 10 in a linepassing between the plungers 18 and 18.A The lockout beams 61-64 are pivotally connected at the ends thereof along longitudinal axes by journals 66 inserted in the end plates 27 and 28. Counterclockwise rotation of the beams 61-64 about the axes, as

n viewed in FIG. 2, is limited by the relative position of the lower edge of projections 67 extending inwardly from the plungers 18, and counterclockwise rotation is limited by the relative position of the lower edge of projections jection overlapping the opposite edge of the beam. Thus K certain push buttons in the other row remain unlocked.

For example, when push button F is depressed, the pro` jection 67 immediately above the edge of the lockout bar 62 will impart counterclockwise rotation thereto and permit only push buttons M, O, Q, R, U and V of push button 17 to be depressed, while push buttons L, N, P, S`

and T are locked out.

ing a push button of the other row., An example of :a

push button operation in connection with FIGS. 5 and 6 will illustrate this principle.

` diseases At the start, the push button row 17 has been clearedof alldepressed buttons. Then push button A of row-16 is depressed. The action ofthe lower edge 41 of the plunger 1S on hooks 39 of the locking bar ,36 will insure that all other push buttons in row 16 are then cleared from a depressed position. Due to notch 70,'the uppermost projection 67 is unobstructed. The beam 6l remains free'about itsaxis so that all of the push buttons in row 17 may still be depressed. However, the next lower pro# jection 67 on the plunger 1S of push button A engages 4the `adjacent edge of the lockout beam 62 there being no notch therein. The beam 62 therefore rotatesvcounterclockwise, as viewed in FIG. 2, so that the opposite side edge of the beam 62 is substantially 'abutting the second tier of the j srojectionsl 67. Because of notches n 69a, b, c'and al in the beam 62, only push buttons M, O,

Q, R,Ujand V of row i7 may still be depressed, the others being locked out. The still next lower projection 67 of the Y plunger it? engages the adjacent edge of the lockout-beam 63 and opposite, notch '71 allows only push buttons O and Q of the previously unlocked push buttons in row i7 to be depressed. Finally, the lockout beam 64 may further reduce the remainder of unlocked push buttons'. ln this instance, however, the beam 64 is not affected due to the notch 7 Z providing unobstructed motion to the bottomv projection 67 on the push button A. This procedure can be followed for all of the other push buttons in either row i6 or f7 and will produce results which are tabulated for this particular example as follows:

Obviously, many variations in unlocked push button combinations are obtainable by varying the notch arrangement without departing from the spirit of this invention. Moreover, the combination may be varied from the possibilities available in the illustrated embodiment by one skilled in the art by varying the number of push buttons in either row or by varying the number of lockout beams.

lt should now be apparent that the present invention is a significant improvement in the electrical switching art wherein only certain of a plurality of electrical circuits are to be connected. The danger that circuits will be connected incorrectly due to human error is obviated. The mechanism for carrying out the circuit selections is relatively simple and compact, of a size suitable for use with airborne instrumentation, and includes relatively few parts for accomplishing a large variety of functions.

It will be understood that various changes in the details, materials, steps and arrangement of parts which have herein been described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

What Vis claimed is:

l. Multiple electric switch apparatus for connecting one circuit with another of a predetermined group of circuits comprising: a support frame formed to be mounted in a control panel, a first plurality of movable push button-'operated plungers slidably mounted on said frame in one row, a second plurality of movable push button-operated plungers slidably mounted on said frame in another row parallel to said one row, each of said plungers being slidable along the length thereof relative to said frame and having a plurality of cam surfaces d spaced along the length thereof, first force-exerting means operatively connected between ,saidframe andl said plungers for urging said plungersto non-depressed posi,-

tions, a first plurality of electrical switches mounted on `r said frame having contacts adapted to be connected to separate circuits and actuator means operatively connected to said plungers, a plurality of .sliding bars slidably mounted on said frame adjacent to said other row of plungers, each of said sliding oars being slidable along the length thereof relative to said frame normal to the length of said plungers, second force-exerting means operatively connected between said frameV and said slidond plurality of electrical switches mounted on said frame having contacts adapted to bie-connected to separate circuits and actuator means operatively connected to said sliding bars foractuation thereby, first and second locking bars slidably mounted on said frame adjacent to respective rows of said plungers and slidable along the lengths thereof relative to said frame normal to the length ofV said plungers, third force-exerting means operatively connected between said frame and said locking bars for urging said locking bars to a locking position, each of said locking bars having a plurality of hooks spaced along the length thereof for engaging an aperture formed in each of said plungers of an adjacent row when any one of said plungers is depressed and said locking bar is in the locking position, said hooks being beveled at the ends thereof for causing one of said locking bars to move to a release position when a corresponding one of said plungers is depressed thereby releasing any other depressed plunger in the same row, iirst and second release rods movably mounted on said frame and operatively connected respectively to said first and second locking bars for moving said locking bars to the releasing position, fourth force-exerting means operatively connected between said frame and said rods for urging said rods to the non-releasing position, each of said plungers further having a plurality of projections spaced along the length thereof extending toward the opposite row, and a plurality of lock-out beams pivotally connected at the ends thereof in said frame between said rows of plungers and normal to the length of said plungers, said beams eing indented along the side edges thereof at selected portions for engaging certain projections and unobstructing others; whereby depressing anyl one push button plunger of either row immobilizes preselected push button plun gers of the opposite row.

puSh button-operated plungers slidably mounted on said frame in one row, a second plurality of movable push button-operated plungers slidably mounted on said frame in another row parallel to said one row, each of said plungers being slidable along the length thereof relative to said frame and having a plurality of cam surfaces spaced along the length thereof, first force-exerting means` operatively connected between said frame and said plungers for urging said plungers to non-depressed positions, a iirst plurality of sliding bars slidably mounted on said frame adjacent to said one row of plungers, a second plurality of sliding bars slidably mounted on said frame adjacent to said other row of plungers, each of said sliding bars being slidable along the length thereof relative to said frame normal to the length of said plungers, second force-exerting means operatively connected between said frame and said sliding bars for urging said sliding bars to one of two actuating positions,

i follower studs selectively inserted along the length of each of said sliding bars for operatively engaging the cam surfaces tof said plungers for causing selected sliding bars to' move to the other actuating position when any one of said plungers is depressed, electrical switches mounted on said frame having contacts adapted to be connected tc separate circuits and actuator means operatively connected to said follower studs for actuation thereby, iirst and second locking bars slidably mounted onv said frame adjacent toy respective rows of said plungers and slidable along the lengths thereof relative to said frame normal j to the length of said plungers, third force-exerting means operatively connected between said frame and said locking bars for urging saidrlocking bars to a locking position, each of said locking bars having a plurality of hooks spaced along the length thereof for engaging an aperture formed in each of said plungers of an adjacent row when any one of said plungers is depressed and said locking bar is in the locking position, said hooks being beveled at the ends thereof for causing one of said locking bars to move to a release position when a corre-l spending one of said plungers is depressed thereby releasing any other depressed plunger in the same row, each of said plungers further having a plurality of projections spaced along the length thereof extending toward the opposite row, and a plurality of lock-out beams Vpivotally connected at the ends thereof in said frame between said rows of plungers and normal to the length of said plungers, said beams being each indented along the side edges thereof at selected portions for engaging certain projections and unobstructing others; whereby depressing vany one push button plunger of either row immobilizespreselected push button plungers of the opposite row.

3. Electrical switch apparatus for connecting one circuit with another of a predetermined group of circuits comprising: a frame, a first plurality of movable push button-operated plungers -slidably mounted on said frame in one row, a second plurality of movable push buttonoperated plungers slidably mounted on said frame in another row parallel to said one row, each of said plungers having a plurality of cam surfaces spaced along the length thereof, a :first plurality of movable bars slidably mounted on said frame adjacent to said one row of plungers, a second plurality of sliding bars slidably mounted on said Vframe adjacent to said other row of plungers, each of said sliding bars being slidable along the length thereof relative to said frame normal to the length of said plungcrs, follower studs selectively inser-ted along the length of each of said sliding bars for operatively engaging the cam surfaces of said plungers Afor causing selected sliding bars to move to `one of two actuating positions when any one of said plungers is depressed, electrical switches adapted to be connetced to separate circuits mounted on said lframe and operatively connected to said sliding bars for actuation thereby, 'first and second locking bars slidably mounted on said drame adjacent to respective rows of said plungers and slidaible along the lengths thereof relative to said Vframe normal to `the length of said plungers, Iforce-exerting means operatively connected between said frame and said locking bars for urging said locking bars to a locking position, each of said locking bars having a plurality of hooks spaced along the length thereof for engaging an aperture formed in each of said plungers of an adjacent row when any one of said plungers is depressed and said locking bar is in the locking position, said hooks being beveled at the ends thereof for causing one of said locking bars to move to a release position when a corresponding one of said .plungers is depressed thereby releasing any other depressed plunger in the same row, each of said plungers having a plurality of projections spaced along the length thereof extending toward the opposite row, and a plurality of lock-out beams pivo'tally connected at the ends thereof in said .frame betweenV said rows of .plungers and normal to the llength of said plunger-s, said beams being each indented along the 4. Electrical switch apparatus for connecting Vone circuit with another of a predetermined groupof circuits comprising: a plurality o-f movable plungers slidably mounted on said lframe arranged in two-rows, each of said plungers having a plurality of cam surfaces spaced along the length thereof, a plurality of movable bars slidably mounted on said frame adjacent to said rows of plungers, each of said sliding bars lbeing slidable along the length thereof relative to said frame normal to the length of :said plungers, tir-st force-exerting means operatively connected between said frame and said sliding bars `for urging said sliding bars to one of two actuating positions, said sliding bars being selectively connected to said plunge'rs at the cam surfaces for causing the connected sliding -bars to move when any one of said plungers is depressed, electrical switches having contacts adapted to be connected to separate circuits mounted on said frame and actuator means operatively connected .to said sliding barsV for actuation thereby, locking means for releasing any other plunger when another plunger in the Same row is depressed, each of said plungers having a c plurality of projections spaced along the length thereof extending toward the opposite row, and a plurality of lock-out beams pivotally connected at the ends thereof in said Iframe between said rows of plungers and normal to the length of said plungers, said beams fbeing each indented along the side edges thereof at selected portions Afor engaging certain projections and unobstructing others;V

whereby depressing any one plunger of one row immobilizes preselected plungers of the opposite row.

5. A multiple push button switch apparatus for preventing preselected electrical circuits from being connected, comprising: a rigid frame, a plurality of longitudinally movable push button-type plungers aligned in a first row slidably mounted in said frame, a plurality ofmovable push button-.type plungcrs slidably aligned in a second row parallel to said first row mounted in said frame, force-exerting means operatively connected between said frame and said plungers for urging said plungers to a nondepressed position, each of said plungers being formed to actuate the armature of a separate electric switch, a plurality of projections on each of said plungers equally spaced along the length thereof and extending toward the row opposite thereof, corresponding projections of each of said rows Vforming tiers normal to the length of said plungers, and a plurali-ty of lock-out Ibeams pivotally connected at the ends thereof -to said frame and nested underneath opposite tiers of said projections, said beams each having the side edges thereof indented at predetermined intervals along the lengths thereof adjacent to preselected projections `of said plungers for'providing unobstructed movement thereof; whereby depressing any one plunger in either of said rows immobilizcs certain plungers in the other of said rows.

6. A multiple push button switch apparatus for preventing preselected electrical circuits from being connected, comprising: a rigid frame, a plurality of longitudinally movable push button-type plunger-s parallel aligned in two row-s slidably mounted in lsaid frame including means for actuating the armatures-of separate electric switches, obstructing means formed on each of said plungers along the length thereof and extending toward the row opposite thereof for preventing movement of said plungers, and a lock-out beam pivotally connected at the ends thereof to said frame between said rows of plungers and nested underneath said obstructing means, said beam having the side :edges thereof indented at 'predeterminedV intervals along the length thereof adjacent to a preselected number of said obstructing means; lwhere-by depressing 7. `A multiple switch apparatus for preventing preselected eletcrical circuits from being connected, comprising: a rigid frame, at lleast one longitudinally movable plunger slidably mounted in said frame, a plurality of longitudinally movable plungers parallel aligned in a row opposite to said oneV plunger slidably mounted in said frame, each of said plungers including means for actuating the armature of a separate .electric switch, a plurality of projections on each of said plungecrs equally spaced along the length thereof and extending toward the opposite plunger, corresponding projections .of said row forming a tier normal to the length of said plungers, and a plurality of lock-out beam-s pivotally connected at the ends thereof to said frame and nested underneath each tier Iof said projections, said beams each having the side edges thereof indented at predetermined intervals along the length thereof adjacent to preselected projections of said plungers Ifor providing unobstructed movement thereof; whereby depressing any one plunger immobilizes certain other plungers.

8. A multiple switch apparatus for'preventing preselected electrical circuits from being connected, comprising: a rigid frame, at least one longitudinally movable plunger slidably mounted in said frame, a plurality of longitudinally movable .plungers parallel aligned in `a row opposite to said one plunger slidably mounted Iin said frame, each of said plungers being .formed to actuate the armature of a separate electric switch, obstructing means formed on each of said plungers along the length thereof and extending toward the plunger opposite thereof, and a lock-out beam pivotally connected at the ends thereof to said frame between said row and said one vplunger and nested underneath said .obstructing means, said lbeam having the side edges thereof indented at predetermined intervals along the length thereof adjacent to a preselected number of said obstructing means; whereby depressing any one plunger immobilizes certain other plungers.

References Cited bythe Examiner UNITED STATES PATENTS 2,200,076 5/40 Cooper. l f 2,831,075 4/5'8 =Dumke ZOO-50 3,118,024 v1/64 Bellinger 200-5 y BERNARD A'.v GlLHEA-NY, Primary Examiner, 

6. A MULTIPLE PUSH BUTTON SWITCH APPARATUS FOR PREVENTING PRESELECTED ELECTRICAL CIRCUITS FROM BEING CONNECTED, COMPRISING: A RIGID FRAME, A PLURALITY OF LONGITUDINALLY MOVABLE PUSH BUTTON-TYPE PLUNGERS PARALLEL ALIGNED IN TWO ROWS SLIDABLY MOUNTED IN SAID FRAME INCLUDING MEANS FOR ACTUATING THE ARMATURES OF SEPARATE ELECTRIC SWITCHES, OBSTRUCTING MEANS FORMED ON EACH OF SAID PLUNGERS ALONG THE LENGTH THEREOF AND EXTENDING TOWARD THE ROW OPPOSITE THEREOF FOR PREVENTING MOVEMENT OF SAID PLUNGERS, AND A LOCK-OUT BEAM PIVOTALLY CONNECTED AT THE ENDS THEREOF TO SAID FRAME BETWEEN SAID ROWS OF PLUNGERS AND NESTED UNDERNEATH SAID OBSTRUCTING MEANS, SAID BEAM HAVING THE SIDE EDGES THEREOF INDENTED AT PREDETERMINED INTERVALS ALONG THE LENGTH THEREOF ADJACENT TO A PRESELECTED NUMBER OF SAID OBSTRUCTING MEANS; WHEREBY DEPRESSING ANY ONE PLUNGER IN EITHER OF SAID ROWS IMMOBILIZES CERTAIN PLUNGERS IN THE OTHER OF SAID ROWS. 